/**
 * pnpm `--reporter=ndjson` progress parser (P1-6).
 *
 * pnpm's ndjson reporter is a bole stream on stdout: one JSON object per
 * line, e.g.
 *
 *   {"time":...,"level":"debug","name":"pnpm:stage","prefix":"...","stage":"resolution_started"}
 *   {"time":...,"level":"debug","name":"pnpm:progress","packageId":"...","status":"resolved"}
 *   {"time":...,"level":"debug","name":"pnpm:fetching-progress","packageId":"...","status":"started","size":123}
 *   {"time":...,"level":"debug","name":"pnpm:ignored-scripts","packageNames":["esbuild"]}
 *   {"time":...,"level":"error","name":"pnpm","err":{"message":"..."}}
 *
 * Verified against real pnpm 11.16.0 output (2026-08). Older pnpm majors
 * emit a different shape or nothing at all — callers fall back to human
 * line parsing when `seen` stays false.
 *
 * The reducer is pure and unit-testable: `feed` mutates the tracker's
 * internal snapshot, `snapshot` returns a serializable copy.
 */

export type ProgressPhase = 'resolving' | 'downloading' | 'linking' | 'building' | null

export interface ProgressSnapshot {
  phase: ProgressPhase
  /** Distinct packages resolved/fetched so far. */
  done: number
  /** Package-count total; pnpm 11's stream carries no per-run total. */
  total: number | null
  /** Package being fetched/linked right now (its `packageId`), or null. */
  currentPackage: string | null
  /** Bytes downloaded for the current package, when known. */
  downloaded: number | null
  /** Total bytes for the current package, when known. */
  size: number | null
  /** True once any structured pnpm event was parsed (ndjson works). */
  seen: boolean
  /** Last fatal error message carried by the stream, if any. */
  error: string | null
  /**
   * pnpm's own error CODE from that same event (`ERR_PNPM_…`), when it
   * carried one. The code is the part that classifies reliably: the message
   * is prose and gets reworded between pnpm releases (#244).
   */
  errorCode: string | null
  /** Package names pnpm reported as having ignored build scripts. */
  ignoredBuilds: string[]
}

export function emptyProgress(): ProgressSnapshot {
  return {
    phase: null,
    done: 0,
    total: null,
    currentPackage: null,
    downloaded: null,
    size: null,
    seen: false,
    error: null,
    errorCode: null,
    ignoredBuilds: [],
  }
}

export interface ProgressTracker {
  readonly snapshot: ProgressSnapshot
  feed(line: string): void
  reset(): void
}

export function createProgressTracker(): ProgressTracker {
  const snap = emptyProgress()
  const seenPackages = new Set<string>()

  function dedupe(packageId: unknown): void {
    if (typeof packageId !== 'string' || packageId === '') return
    if (!seenPackages.has(packageId)) {
      seenPackages.add(packageId)
      snap.done += 1
    }
  }

  function feed(line: string): void {
    let event: unknown
    try {
      event = JSON.parse(line)
    } catch {
      return // human fallback lines are handled by the caller
    }
    if (typeof event !== 'object' || event === null) return
    const msg = event as Record<string, unknown>
    const name = msg.name
    if (typeof name !== 'string') return

    if (name === 'pnpm:stage') {
      const stage = msg.stage
      if (stage === 'resolution_started') snap.phase = 'resolving'
      else if (stage === 'resolution_done') snap.phase = 'downloading'
      else if (stage === 'importing_started' || stage === 'importing_done') snap.phase = 'linking'
      snap.seen = true
      return
    }

    if (name === 'pnpm:progress') {
      snap.seen = true
      const status = msg.status
      if (status === 'resolved') {
        if (snap.phase === null) snap.phase = 'resolving'
        dedupe(msg.packageId)
      } else if (status === 'fetched' || status === 'found_in_store') {
        snap.phase = 'downloading'
        snap.currentPackage = typeof msg.packageId === 'string' ? msg.packageId : snap.currentPackage
        dedupe(msg.packageId)
      }
      return
    }

    if (name === 'pnpm:fetching-progress') {
      snap.seen = true
      snap.phase = 'downloading'
      if (typeof msg.packageId === 'string') snap.currentPackage = msg.packageId
      if (typeof msg.size === 'number') snap.size = msg.size
      if (typeof msg.downloaded === 'number') snap.downloaded = msg.downloaded
      dedupe(msg.packageId)
      return
    }

    if (name === 'pnpm:lifecycle') {
      snap.seen = true
      snap.phase = 'building'
      const wd = typeof msg.wd === 'string' ? msg.wd : ''
      const dep = typeof msg.depPath === 'string' ? msg.depPath : ''
      const base = wd.split(/[\\/]/).filter(Boolean).pop()
      snap.currentPackage = base ?? (dep !== '' ? dep : snap.currentPackage)
      return
    }

    if (name === 'pnpm:stats') {
      // added/removed counts land after the import pass — still linking.
      if (msg.added !== undefined || msg.removed !== undefined) snap.phase = 'linking'
      snap.seen = true
      return
    }

    if (name === 'pnpm:ignored-scripts') {
      snap.seen = true
      if (Array.isArray(msg.packageNames)) {
        for (const pkg of msg.packageNames) {
          // pnpm's ndjson event reports version-qualified names (cloudflared@0.7.3);
          // the approve-builds allowlist keys and node_modules lookups use bare
          // package names, so strip the suffix (same rule as the human-line
          // fallback in install.ts's parseIgnoredBuilds).
          const at = typeof pkg === 'string' ? pkg.lastIndexOf('@') : -1
          const bare = at > 0 ? pkg.slice(0, at) : pkg
          if (typeof bare === 'string' && bare !== '' && !snap.ignoredBuilds.includes(bare)) snap.ignoredBuilds.push(bare)
        }
      }
      return
    }

    if (name === 'pnpm' && msg.level === 'error') {
      const err = (msg.err ?? {}) as Record<string, unknown>
      const message = typeof err.message === 'string' ? err.message : ''
      // Keep more than the old 400: ERR_PNPM_UNEXPECTED_STORE spends most of
      // its message naming two absolute store paths, and truncating them is
      // exactly the information a user needs to fix it by hand (#244).
      if (message !== '') snap.error = message.slice(0, 2000)
      if (typeof err.code === 'string' && err.code !== '') snap.errorCode = err.code
      return
    }
  }

  function reset(): void {
    seenPackages.clear()
    const fresh = emptyProgress()
    Object.assign(snap, fresh)
  }

  return {
    get snapshot(): ProgressSnapshot {
      return { ...snap, ignoredBuilds: [...snap.ignoredBuilds] }
    },
    feed,
    reset,
  }
}